users are not presented with an option to accept, decline, or tentative appointments

As the topic says, sometimes users are not presented with an option to accept, decline, or tentative an appointment. The do receive a meeting request email, but in some cases that email offers no options for accepting, declining, or tentative.

However, the user can go to their calendar and right click on the appointment in question, and _then_ select one of the above options. This works fine, without issue.

accept, decline, reject issue - RU using Outlook 2003?

If yes, we have found that applying latest patches to all PCs resolves this issue.

If some users are on SP2 while others are on SP3 or some have the latest outlook only patches and others don't we see the issue but as soon as we patch everyone to the latest level we don't see the issue.